The law of independent assortment states that “when two parents differing from each other in two or more pairs of contrasting characters are crossed, then the inheritance of one pair of character is independent of the other pair of character.”
For example, when we cross a pure tall, red flowered pea plant with a pure dwarf white flowered pea plant, we get 9 tall red, 3 tall white, 3 dwarf red and 1 dwarf white plants in the F2 generation. A cross between two homozygous individuals differing in two pairs of contrasting characters is called dihybrid cross.
Result: Tall red = 9 ;Tall white = 3; Dwarf red = 3; Dwarf white = 1
Phenotypic ratio → 9 : 3 : 3 : 1
Genotypic ratio →
From the above results, it is obvious that the inheritance of character of tallness in no way linked with the red colour of the flower. Similarly, the character of dwarfness is not linked with the white colour of the flower. This is due to the fact that in the above cross, the two pairs of characters segregate independently. In other words, there is independent assortment of characters during inheritance.
